CN109920945B - Battery pack - Google Patents
Battery pack Download PDFInfo
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- CN109920945B CN109920945B CN201811507035.9A CN201811507035A CN109920945B CN 109920945 B CN109920945 B CN 109920945B CN 201811507035 A CN201811507035 A CN 201811507035A CN 109920945 B CN109920945 B CN 109920945B
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- battery
- insulator
- battery pack
- battery cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/04—Construction or manufacture in general
- H01M10/0481—Compression means other than compression means for stacks of electrodes and separators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
- H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
- H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
- H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
- H01M50/262—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders with fastening means, e.g. locks
- H01M50/264—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders with fastening means, e.g. locks for cells or batteries, e.g. straps, tie rods or peripheral frames
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
- H01M50/289—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs
- H01M50/293—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs characterised by the material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Battery Mounting, Suspending (AREA)
- Connection Of Batteries Or Terminals (AREA)
Abstract
The invention provides a battery pack which prevents a joint between a bus bar and an electrode from being broken. The battery pack includes: a plurality of battery cells arranged in a row in one direction; a pair of end plates that sandwich a plurality of battery cells in a row from both ends in the arrangement direction of the plurality of battery cells; a pair of tie bars that sandwich the plurality of battery cells from a direction perpendicular to the arrangement direction and fasten a pair of end plates at both ends in the arrangement direction; and an insulator sandwiched in the gap between the connection rod and the battery cell, the insulator being in a compressed state in which an initial thickness before insertion into the gap is larger than the gap.
Description
Technical Field
The present invention relates to a battery pack in which a plurality of battery cells are arranged in one direction.
Background
A conventional battery pack is known to use a method of laser welding electrode terminals and bus bars when a plurality of battery cells are arranged in series and the electrode terminals positioned at both ends of the adjacent battery cells are connected by current collectors called bus bars (see, for example, patent document 1).
Fig. 6 is a schematic perspective view showing the overall structure of the conventional battery pack disclosed in patent document 1. Fig. 6 is an overall view of a conventional battery pack. In this figure, the battery pack 1 is configured such that a plurality of battery cells 2 are arranged in series, and end plates 3 are connected and fixed by tie bars 4 extending in the arrangement direction while both ends of the battery cells are sandwiched by the end plates 3. Further, electrode terminals are provided on the upper surfaces of the battery cells 2, and one of the electrode terminals of the adjacent battery cells 2 is joined by a bus bar 5.
Prior art documents
Patent literature
Patent document 1: international publication No. 2014/034106
In recent years, as represented by the battery pack of patent document 1, welding by laser or the like has been often used for joining the electrode terminals of the lithium ion secondary battery and the bus bars. As a method of joining electrode terminals of a battery pack heretofore, a method of joining bus bars by screwing the electrode terminals and fastening them with bolts is used, but joining using laser welding has an advantage of having fewer processes than screw locking. In contrast, laser welding has a disadvantage that the strength of the joint is weak as compared with bolt fastening. For example, when a load due to impact, vibration, or the like is applied to the assembled battery, the load is generated at the bus bar welded portion due to displacement of the battery cells constituting the assembled battery. Further, if the load becomes too large, there is a possibility that a fracture may occur in the welded portion. In particular, when a large impact is applied in the direction in which the battery cells are arranged in series (hereinafter referred to as the arrangement direction, which is referred to as the y direction), the battery cells that are not restrained by the end plates in the arrangement direction are largely displaced as shown in fig. 2A. As a result, a large load is generated also in the welded portion, which is very dangerous.
Disclosure of Invention
The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a battery pack in which breakage at a joint portion between a bus bar and an electrode is suppressed.
In order to achieve the above object, a battery pack according to the present invention includes: a plurality of battery cells arranged in a row in one direction; a pair of end plates that sandwich the plurality of battery cells in the row from both ends in the arrangement direction of the plurality of battery cells; a pair of tie bars that sandwich the plurality of battery cells from a direction perpendicular to the arrangement direction and fasten the pair of end plates at both ends of the arrangement direction; and an insulator sandwiched in a gap between the connection bar and the battery cell, the insulator being in a compressed state in which an initial thickness before insertion into the gap is larger than the gap.
Effects of the invention
As described above, the battery pack according to the present invention includes an insulator such as rubber or resin that is interposed between the tie bar and the battery cell. Therefore, even when a large external force is applied in the arrangement direction of the plurality of battery cells, the displacement of the battery cells in the direction of the external force can be reduced by the friction with the insulator such as rubber or resin interposed between the tie bar and the battery cells, and the breakage of the joint between the bus bar and the electrode can be suppressed. In addition, the insulation is in a compressed state with an initial thickness greater than the gap prior to insertion into the gap. Thereby, the above-described effects can be achieved with little change in the outer dimensions of the battery pack.
Drawings
Fig. 1A is a schematic perspective view showing the overall structure of a battery pack according to embodiment 1 of the present invention.
In fig. 1B, (base:Sub>A) is an exploded view showing the structure of the battery cells, thin insulators, and tie bars between the battery cells and the end plates at one end of the battery pack of fig. 1A, and (B) isbase:Sub>A schematic sectional view showing only the battery cells, tie bars, and insulators of (base:Sub>A) inbase:Sub>A section of the battery pack that passes through an imaginary linebase:Sub>A-base:Sub>A' of the battery pack of fig. 1A and is perpendicular to the arrangement direction (y direction).
In fig. 1C, (base:Sub>A) is an exploded view showing the structure of the battery cells, thick insulators, and tie bars between the battery cells and the end plates at one end of the battery pack of fig. 1A, and (b) isbase:Sub>A schematic cross-sectional view showing only the battery cells, tie bars, and insulators of (base:Sub>A) inbase:Sub>A cross section of the battery pack passing through an imaginary linebase:Sub>A-base:Sub>A' of the battery pack of fig. 1A and perpendicular to the arrangement direction (y direction).
Fig. 2A is a diagram showing the movement of members when the battery pack according to embodiment 1 of the present invention receives an impact in the array direction, and (b) is a schematic diagram showing a case where each battery cell is compressed in the array direction by the impact in the array direction of (a).
In fig. 2B, (a) is a schematic cross-sectional view showing a cross-sectional structure of the battery pack in which a thin insulator having the same initial thickness as the gap between the battery cell and the tie bar is interposed between the battery cell and the tie bar, as in fig. 1B (B), and (B) is a schematic cross-sectional view showing deformation of the tie bar when the battery pack of (a) is subjected to an impact in the arrangement direction.
In fig. 2C, (a) is a schematic cross-sectional view showing a cross-sectional structure of the battery pack in which an insulator having an initial thickness larger than the gap is interposed between the battery cells and the tie bars in the same manner as in fig. 1C (b), and (b) is a schematic cross-sectional view showing deformation of the tie bars and restoration of the insulator when the battery pack of (a) receives an impact in the arrangement direction.
Fig. 3 is a model diagram of simulation according to embodiment 1 of the present invention.
Fig. 4 is a contour diagram showing the gap between the tie bar and the battery cell obtained in the simulation according to embodiment 1 of the present invention.
Fig. 5A is a graph showing a relationship between a peeling force acting on a welded portion of an electrode and a bus bar and a compression ratio of an insulator, which are obtained in the simulation according to embodiment 1 of the present invention.
Fig. 5B is a graph showing a relationship between the coefficient of friction and the compressibility of the insulator.
Fig. 6 is a schematic perspective view showing the overall structure of a conventional battery pack disclosed in patent document 1.
Description of the symbols
1. Battery pack
2. Battery unit
3. End plate
4. Connecting rod
5. Bus bar
6. Electrode terminal
7. Insulating material
8. Clamp apparatus
9. Battery case
11. Impact of
Detailed Description
The battery pack according to claim 1 includes: a plurality of battery cells arranged in a row in one direction; a pair of end plates that sandwich the plurality of battery cells in the row from both ends in the arrangement direction of the plurality of battery cells; a pair of tie bars that sandwich the plurality of battery cells from a direction perpendicular to the arrangement direction and fasten the pair of end plates at both ends of the arrangement direction; and an insulator sandwiched in a gap between the connection bar and the battery cell, the insulator being in a compressed state in which an initial thickness before insertion into the gap is larger than the gap.
The battery pack according to claim 2 is the battery pack according to claim 1, wherein the friction coefficient between the battery cell, the tie bar, and the insulator is μ, and the pressure of the insulator is set to μWhen the reduction rate is Δ L, the following relationship can be satisfied: when mu is more than 0.2 and less than 0.4, delta L>13μ2-11.55 μ +2.63; when mu is not more than 0.4, delta L>0.125μ2-0.275μ+0.18。
In the battery pack according to claim 3, in the above-described 1 or 2, the insulator may be bonded to at least one of the tie bar and the battery cell.
In the battery pack according to claim 4, in any one of the above-described 1 to 3, when a mounting surface of the electrode of the battery cell is an upper side, the initial thickness of the insulator may be increased as approaching the upper side.
Hereinafter, a battery pack according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, substantially the same components are denoted by the same reference numerals.
(embodiment mode 1)
Fig. 1A is a perspective view showing the entire battery pack 1 according to embodiment 1 of the present invention. Fig. 1B (a) is an exploded view showing the structure of the battery cells 2, the thin insulators 7, and the connection rods 4 between the battery cells 2 and the end plates 3 at one end of the battery pack 1 of fig. 1A. Fig. 1B (B) isbase:Sub>A schematic cross-sectional view showing only the battery cells 2, tie bars 4, and insulators 7 of (base:Sub>A) inbase:Sub>A cross section of the battery pack 1 that passes through the broken linebase:Sub>A-base:Sub>A' of the battery pack 1 of fig. 1A and is perpendicular to the arrangement direction (y direction). Fig. 1C (a) is an exploded view showing the structure of the battery cells 2, the thick insulator 7, and the tie bars 4 between the battery cells 2 and the end plates 3 at one end of the battery pack 1 of fig. 1A. Fig. 1C (b) isbase:Sub>A schematic cross-sectional view showing only the battery cells 2, tie bars 4, and insulators 7 of (base:Sub>A) inbase:Sub>A cross section of the battery pack 1 that passes through the broken linebase:Sub>A-base:Sub>A' of the battery pack 1 of fig. 1A and is perpendicular to the arrangement direction (y direction).
In fig. 1A, the same reference numerals are used for the same components as those in fig. 6. The battery pack 1 according to embodiment 1 includes a plurality of battery cells 2, end plates 3, tie bars 4, and insulators. The battery unit 2 is a basic component of a battery, and stores electricity generated by the power generation device to supply power to an electric product or equipment connected as necessary. The plurality of battery cells 2 are arranged in series. One end plate 3 is disposed at each of both ends of the plurality of battery cells 2, and the plurality of battery cells 2 are sandwiched from both ends in the arrangement direction by the end plates 3, respectively, disposed in contact with the battery cells at both ends. The plurality of battery cells 2 are held from the direction perpendicular to the arrangement direction by the tie bars 4. The pair of end plates 3 are coupled to each other by a connecting rod 4 by riveting, welding, or bolting. Since it is very dangerous to directly couple the battery cells 2 located at both ends of the battery pack 1 to the connection rods 4, the end plates 3 are used. A metal material such as aluminum or iron is often used for the end plate 3. In this case, measures such as sandwiching an insulating material between the end plate 3 and the battery cells 2 at both ends are taken. Since the battery cells 2 expand during repeated charge and discharge, a metal material having high tensile strength, such as high-strength steel, is used for the tie rods 4.
Further, in the battery pack 1 according to embodiment 1, as shown in fig. 1C (a), an insulator 7 having an initial thickness larger than the gap is interposed between the battery cells 2 and the tie bars 4. As the insulator 7, for example, a rubber or resin material, the original thickness (initial thickness) is thicker than the gap size. When assembled into the battery pack 1, the insulator 7 is sandwiched between the gaps in a compressed state (compressed state) as shown in fig. 1C (b).
As shown in fig. 1B (a), even when the insulator 7 has a thickness substantially equal to that of the gap, the insulator 7 is sandwiched between the gaps in a state where the thickness is unchanged as shown in fig. 1B (B) when the assembled battery 1 is assembled.
< case where a large external force is applied in the alignment direction >
In the conventional battery pack 1 as in patent document 1, when a large external force is applied in the arrangement direction, a large peeling force is likely to be generated at the welded portion between the electrode terminal 6 and the bus bar 5. This is because there is no object other than the end plates 3 that restrains the displacement of the battery cells 2 in the arrangement direction, and the battery cells 2 easily move in that direction. On the other hand, regarding the directions other than the arrangement direction, since the tie bars 4 restrain the displacement of the battery cells, it is considered that the movement is less likely than in the arrangement direction, and the displacement is suppressed to be small.
Fig. 2A (a) is a diagram showing the movement of the members when the battery pack 1 of embodiment 1 receives the impact 11 in the arrangement direction, and (b) is a schematic diagram showing a case where each battery cell is compressed in the arrangement direction by the impact 11 in the arrangement direction of (a). Fig. 2B (a) is a schematic cross-sectional view showing the cross-sectional structure of the battery pack in which a thin insulator 7 having the same initial thickness as the gap between the battery cell 2 and the tie bar 4 is interposed in the gap as in fig. 1B (B). Fig. 2B (B) is a schematic cross-sectional view showing deformation of the tie bars 4 when the battery pack of fig. 2B (a) receives an impact in the arrangement direction. Fig. 2C (a) is a schematic cross-sectional view showing a cross-sectional structure of a battery pack in which an insulator 7 having an initial thickness larger than the gap is interposed between the battery cell 2 and the tie bar 4, as in fig. 1C (b). Fig. 2C (b) is a schematic cross-sectional view showing deformation of the tie bars 4 and restoration of the insulator 7 when the battery pack of fig. 2C (a) is subjected to an impact in the arrangement direction. Fig. 2B and 2C are sectional views atbase:Sub>A-base:Sub>A' of fig. 1A, similar to fig. 1B and 1C.
When a large impact 11 is applied in the arrangement direction (y direction), the battery pack 1 is deformed as shown in fig. 2A to 2C. That is, as shown in fig. 2A (a) and (b), each battery cell 2 is in a compressed state in which it is collected forward in the impact direction (y direction). Further, as shown in fig. 2B (B) and 2C (B), the tie bars 4 are deformed to expand convexly outward, i.e., in the x direction, from the battery pack 1.
First, if the thickness of the insulator 7 is thin, as shown in fig. 2B (B), the intervals between the battery cells 2 and the insulator 7 and between the insulator 7 and the tie bars 4 become wide, and the contact between the insulator 7 and the tie bars 4 cannot be ensured. As a result, the frictional force generated by the insulator 7 does not act, and the displacement of the battery cells 2 in the arrangement direction (y direction) cannot be suppressed.
On the other hand, in embodiment 1, as shown in fig. 1C (a), the insulator 7 of the gap between the battery cell 2 and the tie bar 4 is formed to have a thickness larger than the interval between the two, and is sandwiched while being compressed when the battery pack 1 is assembled. As a material of the insulator 7, for example, rubber or a resin material having a high ultimate compression rate can be used. With such a configuration, even when a large impact is applied in the arrangement direction, even if the gap between the battery cell 2 and the tie bar 4 is widened, the gap can be always filled with the insulator 7 by restoring the compressed insulator 7 to the original thickness as shown in fig. 2C (b). This ensures a contact state between the battery cells 2 and the insulator 7, and between the insulator 7 and the tie bars 4, and allows frictional force to act between these objects, thereby suppressing displacement of the battery cells 2 in the arrangement direction.
When the installation surface of the electrode terminal 6 of the battery cell 2 is set to be the upper side, that is, the vertically upper side (z direction), the initial thickness of the insulator 7 may be increased as the upper side is approached. By providing the initial thickness of the insulator 7 in this manner, particularly in the upper portion where the gap is likely to be widened, the frictional force can be efficiently exerted, and displacement of the battery cells 2 in the arrangement direction can be suppressed.
(examples)
In order to confirm the effect of the present invention, simulations were performed as examples.
Fig. 3 is a model diagram of a battery pack 1 used in a simulation and a jig 8 for fixing the battery pack 1. In this model, it is assumed that the battery pack 1 is mounted on a vehicle such as an electric vehicle or a stationary type. The battery pack 1 is fastened at four corners by bolts to the jigs 8, and the jigs 8 are structures that completely fix the bottom surface. In this state, a case where an impact of 80G is given to the battery pack 1 in the arrangement direction is considered.
In the battery pack 1 shown in fig. 4, the gap between the side surface of the battery cell 2 and the tie bar 4 is set to 0.1mm. As the insulator 7 sandwiched between the battery cells 2 and the tie bars 4, a resin having a young's modulus of 2.45GPa was used, and the initial thicknesses were 0.1mm, 0.105mm, 0.12mm, 0.14mm, 0.16mm, and 0.18mm, which were the same as the above gaps. Regarding five thicknesses of the initial thickness of 0.105mm to 0.18mm, the thickness immediately after assembly was 0.1mm, being sandwiched between the battery cells 2 and the tie bars 4 when the battery pack 1 was assembled. The coefficient of friction between the insulator 7 and the battery cell 2 and the tie bar 4 is varied from 0.2 to 0.8 in consideration of the contact and friction between the members. The friction coefficient of an actual device can be measured by a test method JISK7125 determined by JIS standard.
For this model, boundary conditions are given to the battery pack 1 in the following order.
1) The battery cells 2 are slightly expanded, and a binding force is applied to the battery cells 2. This corresponds to a reaction force generated when the battery cells 2 and the end plates 3 arranged in series are temporarily compressed when the battery pack 1 is assembled, and then the end plates at both ends are fixed by the tie bars.
2) In order to simulate the case where the bus bar 5 is placed at a predetermined position and welded, the displacement in all directions is set to be the same for the welding surfaces of the corresponding electrode and bus bar.
3) The bolts at the four corners of the battery pack 1 are provided with screw fastening force for fixing to the jig 8, and the battery pack 1 is fixed to the jig 8.
4) The impact 11 of 80G is applied in the arrangement direction (y direction), i.e., the direction in which the battery cells 2 are arranged in series.
The effect of the battery pack according to the present invention will be described below using a simulation result. Here, for convenience of explanation, among the directions perpendicular to the arrangement direction (y direction) of the battery cells 2, the direction perpendicular to the large plane of the tie bar 4 is defined as the x direction.
Fig. 4 is a contour diagram showing the gap between the tie bar and the battery cell obtained in the simulation according to embodiment 1 of the present invention. In fig. 4, the contour of the gap (displacement difference in the x direction) between the short side of the battery cell 2 parallel to the large plane of the tie bar 4 and the large plane of the tie bar 4 in the structure of the battery pack 1 with the initial thickness of the insulator 7 of 0.1mm is shown. In the figure, the portion where the gap indicated by hatching is 0.1 or less indicates a case where the battery cell 2 and the tie bar 4 are in contact with each other through the insulator 7. A portion where the gap is larger than 0.1 indicates that a gap is generated between the insulator 7, the battery cell 2, and the tie bar 4, that is, that contact cannot be ensured. Since the battery pack 1 receives an impact in the arrangement direction (y direction) in a state where the four corners are fixed to the jigs 8, a compressive force acts on the battery cells in the arrangement direction (y direction). This causes displacement to bulge outward in the x direction. On the other hand, the tie bars 4 are also subjected to a compressive force in the arrangement direction, and a large plane bulges outward, causing displacement in the x direction. A gap is formed at a portion of the tie bar 4 where the displacement in the x direction is large, and a portion where the displacement is small can ensure contact with the battery cell 2 and the insulator 7. Since the lower side of the battery pack 1 is close to the point where it is fixed to the jig 8, the battery cells 2 and the tie bars 4 are not easily moved, and therefore, a gap is hardly generated. On the other hand, the gap is generated more upward, and the gap is generated in an area of about 45% of the surface where the battery cell 2 and the tie bar 4 are initially in contact. It appears in this region that the friction of the battery cells 2, the insulation 7 and the connecting rods 4 does not function effectively. At this time, the maximum value of the peeling force generated at the welded portion between the electrode and the bus bar exceeds the allowable value as shown in fig. 5A.
Based on the results shown in fig. 4, it is considered that if the initial thickness of the insulator 7 is greater than 0.1mm (the compressibility is set to be greater than 0), the friction can effectively act also in the above-described region.
Fig. 5A is a graph showing a relationship between a peeling force applied to a welded portion of an electrode and a bus bar and a compression ratio of an insulator, which is obtained in the simulation according to embodiment 1 of the present invention. Fig. 5B is a graph showing the relationship between the friction coefficient and the compression rate of the insulator. Fig. 5A shows the result of calculating the maximum value of the peeling force generated at the welded portion between the electrode and the bus bar when the initial thickness is set to 0.105mm to 0.18mm, and plotting the relationship. Here, the horizontal axis represents the compressibility of the insulator, and is defined as follows.
Compressibility of the insulator = (initial thickness of insulator-initial gap of battery cell and connection rod)/initial thickness of insulator
=1- (initial gap of battery cell and connecting rod/initial thickness of insulator)
That is, the compression rates are 0.048, 0.167, 0.286, 0.375, 0.444 for the initial thicknesses of the insulator 7 of 0.105mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm, respectively. Further, the compression ratio was zero at an initial thickness of 0.1mm. The maximum peeling force of the welded portion shown in the vertical axis of fig. 5A is represented by a non-dimensionalized peeling force of the welded portion, with a value of 1 when the initial thickness of the insulator 7 is 0.1mm. As is clear from fig. 5, the maximum peeling force of the welded portion becomes smaller as the compression ratio becomes larger, and friction effectively acts via the compressed insulator 7, and displacement of the battery cell 2 due to impact can be suppressed.
When the non-dimensionalized weld separation force shown in fig. 5A is used as an index, the allowable value in design is smaller than 0.67 shown by a broken line in fig. 5A. When the initial thickness of the insulator is 0.1mm, the value is 1, which exceeds the allowable value, but when the coefficient of friction is 0.4, for example, the compression ratio is set to 0.09 or more, whereby the allowable value can be reduced. Therefore, it becomes a compression ratio required for the insulator 7. Further, when the friction coefficient is 0.2, even if the compression ratio is increased, the non-dimensionalized weld separation force is not less than the allowable value, and therefore, it is understood that the friction coefficient must be more than 0.2. Thus, from fig. 5A, when the compression ratio with which the dimensionless weld separation force is less than 0.67 is obtained for each friction coefficient, the relationship can be represented by a graph shown in fig. 5B. If the maximum peeling force at the welded portion is kept to be equal to or less than the allowable value if the maximum peeling force is present in the upper region of the graph shown in fig. 5B, it is understood that the friction coefficient μ and the compression ratio Δ L may satisfy the following equation.
Delta L when mu is more than 0.2 and less than 0.4>13μ2-11.55μ+2.63
Δ L when [ mu ] is 0.4 or less>0.125μ2-0.275μ+0.18
The material and the initial size of the insulator 7 may be selected so as to satisfy the above formula. As the material, rubber or resin is used, and in the case where flame retardancy is required when the material is used in a battery pack, chloroprene rubber, nitrile rubber, styrene-butadiene rubber, EPDM (propylene-ethylene), PTFE (fluororesin), polyurethane, polyethylene, polycarbonate, PBT (polybutylene terephthalate), modified PPE (polyphenylene ether), and the like are desired. In these materials, the coefficient of friction with the case of the battery cell 2 or the tie bar 4, which is a metal material, is usually greater than 0.4, and a compressibility of greater than 0.1 (10%) is sufficient. Materials other than those described above may be used as long as they satisfy the above formula, but most rubbers and resins have a limit compressibility of less than 40%, and therefore a friction coefficient of 0.3 or more is desirable. Further, as is clear from the graph of fig. 5A, the friction coefficient is preferably 0.3 or more because the nondimensional peeling force is not less than the allowable value when the friction coefficient is 0.2.
(embodiment mode 2)
In the case where the outer surface of the battery cell 2 is made of a metal material or the tie bar 4 is made of a metal material, the surface is roughened to increase the friction coefficient, thereby providing an effect better than that of the method described in embodiment 1. For example, if the material of the tie rod 4 is a steel material that is usually used, the friction coefficient becomes about 0.4 when the average roughness Ra is 5 to 10 μm. If the average roughness is set to be larger than 10 μm, the friction coefficient can also be increased to a certain value, but if the contact area at the outermost surface of the member becomes small, the effect of friction may be reduced when the battery pack 1 receives an impact and the distance between the battery cell 2, the insulator 7, and the tie bar 4 becomes large.
The present invention includes a case where any of the foregoing various embodiments and/or examples is appropriately combined, and effects of the various embodiments and/or examples can be obtained.
Industrial applicability
The battery pack of the present invention is applicable to transportation equipment such as electric vehicles and hybrid vehicles, household storage batteries, emergency power supplies, and the like.
Claims (6)
1. A battery pack is provided with:
a plurality of battery cells arranged in a row in one direction;
a pair of end plates that sandwich the plurality of battery cells in the row from both ends in an arrangement direction of the plurality of battery cells;
a pair of tie bars that sandwich the plurality of battery cells from a direction perpendicular to the arrangement direction and fasten the pair of end plates at both ends of the arrangement direction; and
an insulator interposed in a gap between the connection bar and the battery cell,
the insulation is in a compressed state having an initial thickness greater than the gap prior to insertion into the gap,
the connecting rod is in direct contact with the upper surface and the lower surface of the battery unit and is in a shape of a letter '124676767',
the insulator is not provided on the upper surface and the lower surface of the battery cell, and is provided on the entire side surface of the battery cell in a direction perpendicular to the arrangement direction,
the insulator is in direct contact with the connection bar and is in direct contact with the battery cell at the entire side.
2. The battery pack according to claim 1,
when the coefficient of friction between the battery cell and the connection rod and the insulator is μ and the compressibility of the insulator is Δ L, the following relationship is satisfied:
when mu is more than 0.2 and less than 0.4, delta L is more than 13 mu2-11.55μ+2.63；
When the diameter is not less than 0.4, the Delta L is more than 0.125 mu2-0.275μ+0.18。
3. The battery pack according to claim 1,
the insulator is bonded to at least one of the tie bar or the battery cell.
4. The battery pack according to any one of claims 1 to 3,
when the mounting surface of the electrode of the battery cell is set to be the upper side, the initial thickness of the insulator increases as the initial thickness approaches the upper side.
5. The battery pack according to any one of claims 1 to 3,
adjacent ones of the plurality of battery cells are connected to each other via bus bars on upper surfaces of the plurality of battery cells.
6. The battery pack according to claim 4,
adjacent ones of the plurality of battery cells are connected to each other via bus bars on upper surfaces of the plurality of battery cells.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017238850A JP2019106318A (en) | 2017-12-13 | 2017-12-13 | Battery pack |
| JP2017-238850 | 2017-12-13 |
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| Publication Number | Publication Date |
|---|---|
| CN109920945A CN109920945A (en) | 2019-06-21 |
| CN109920945B true CN109920945B (en) | 2022-11-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201811507035.9A Active CN109920945B (en) | 2017-12-13 | 2018-12-11 | Battery pack |
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| US (1) | US11283099B2 (en) |
| JP (1) | JP2019106318A (en) |
| CN (1) | CN109920945B (en) |
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| JP2022169375A (en) * | 2021-04-27 | 2022-11-09 | トヨタ自動車株式会社 | Battery pack and manufacturing method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1874030A (en) * | 2005-06-02 | 2006-12-06 | 株式会社东芝 | Battery pack of assembled battery and fixing method of assembled battery |
| WO2017057082A1 (en) * | 2015-10-02 | 2017-04-06 | 日立オートモティブシステムズ株式会社 | Assembled battery |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101067625B1 (en) | 2008-03-07 | 2011-09-26 | 주식회사 엘지화학 | Middle and Large-Sized Battery Module Having Electrode Terminal Connecting Member and Insulating Joint Member |
| CN102696131B (en) | 2010-11-30 | 2015-09-23 | 松下知识产权经营株式会社 | Battery modules and power brick |
| JP2015207340A (en) | 2012-08-30 | 2015-11-19 | 三洋電機株式会社 | Power unit, electric vehicle with power unit, power storage device, and manufacturing method of power unit |
| US9616766B2 (en) * | 2012-08-30 | 2017-04-11 | Sanyo Electric Co., Ltd. | Power source device, vehicle provided with power source device, and power storage device |
| JP6355347B2 (en) * | 2014-01-30 | 2018-07-11 | 日立建機株式会社 | Hybrid construction machine |
| JP2016119155A (en) * | 2014-12-18 | 2016-06-30 | 株式会社豊田自動織機 | Power storage device pack |
| JP6759184B2 (en) * | 2015-02-27 | 2020-09-23 | 三洋電機株式会社 | Power supply and vehicle equipped with it |
| JP6728576B2 (en) * | 2015-05-12 | 2020-07-22 | 株式会社豊田自動織機 | Battery pack |
| JP6058738B2 (en) | 2015-05-21 | 2017-01-11 | 株式会社東芝 | Bus bar and battery module |
| WO2017017914A1 (en) * | 2015-07-30 | 2017-02-02 | 三洋電機株式会社 | Power supply device, power supply system provided with said power supply device, and separator for battery cells |
| JP6620655B2 (en) * | 2016-04-20 | 2019-12-18 | 株式会社豊田自動織機 | Battery module |
| WO2019031169A1 (en) * | 2017-08-07 | 2019-02-14 | 三洋電機株式会社 | Battery module and vehicle equipped with same |
-
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- 2017-12-13 JP JP2017238850A patent/JP2019106318A/en active Pending
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- 2018-12-10 US US16/214,418 patent/US11283099B2/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1874030A (en) * | 2005-06-02 | 2006-12-06 | 株式会社东芝 | Battery pack of assembled battery and fixing method of assembled battery |
| WO2017057082A1 (en) * | 2015-10-02 | 2017-04-06 | 日立オートモティブシステムズ株式会社 | Assembled battery |
Also Published As
| Publication number | Publication date |
|---|---|
| US20190181488A1 (en) | 2019-06-13 |
| JP2019106318A (en) | 2019-06-27 |
| CN109920945A (en) | 2019-06-21 |
| US11283099B2 (en) | 2022-03-22 |
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